Process of recovering paraffin from paraffin-containing materials



Patented Mar. 1 1.932

UNITED STATES l rri31-rr`v .OFFICE HANS OLOF LINDGREN', 0F STOCKHOLM,KN'UT GIJ'STAIE OF SALTSJOBADEN,

SWEDEN, ASSIGNORS TO THE DE LAVAL SEPARATOR COMPANY, OF NEW YORK, N.Y.,'

` A CORPORATION OF NEW JERSEY PROCESS OF RECOVERING PARAFFIN FROMPARAFFIN-CONTAINING MATERIALS v Application led'May 17, 1924, Serial No.714,175, and in Germany J'une 28, 1923.l

The present invention relates to the treatment of materialscontainingparafiin, such as (l) crude' oils or tars containing paraffin,in order to produce lubricating oils with a low cold test and parafiinsof high quality;

(2) amorphous paraifin containing liquid hydrocarbons, natural paratlinscontaining oils, and other materials containing parain, in order toproduce either (a) crystallized paraffins, or (b) refined amorphousparaffin with a high melting point; (3) distillates or residuum(containing paraflin) from crude oil or tar, in order to produce highgrade paraffin of uniform composition.

Our process is adapted to the treatment of allthe above specifiedmaterials "for secur' ing all the above specified products; and whilethe Way of carrying out the process is substantially the same in allcases, the procedure,'as applied to each of the specified basematerials, is herein fully described.

Treatment of crude oils and tft-rs containing Parafia, to produceZubwfcatz'mg oils 'with a low cold test and pamyns with a high meltmg27o/mt filtered oif by means of filter presses. The.

oil relieved of paraffin is then redistilled in order to obtainlubricating oils. This process is objectionable, because 'the precedingdistillation must be effected in such a way that the viscosity of theoil is highly reduced, 5 'as paraiin crystallizes only with dificultyout of oils Withhigh viscosities and is then very difficult to filteroff,

If the crude oil contains only very small quantities of asphalt,theresidues left after distilling off benzine, burning oils and para finoil are treated directly for producing 1ubricatingoils with high.viscosities These residues, however, contain the paraiin' as Wax(amorphous paraiiin), `which is precipitated in a form that cannot befiltered, inasmuch as the mass will block the'filters at once.Therefore, such residue is usually diluted with gasoline or naphtha,then cooled and caused to stand in large tanks, and on Aaccount of itshigher specific gravity the amorphous paraffin settles-by gravity. There1s thus obtained an upper'layer of a relaltivelyparaiiin-free oil whichis used for the manufacture of highly viscous oil, and a lower layer ofa heavy mass rich in paraffin. This method certainly avoids inipalringthe viscosity of the heavyoil by cracking incidental to ordinaryfractional distillation, but the paraiiin is incompletely precipitatedand the oil obtained has a rather high'cold test. F urther, themethod-is very time-consuming, and large quantities of gasoline and oilare always tied up in the manufacturing procedure.

.It has also been proposed to' treat this residue, after dilution andVcooling, by means of centrifuges, whereby the separated paraffin iscaused to deposit at the periphery of the separator bowl, from Where itis removed in some Way or other continuously, ifpossible.

It has been also proposed to dilute the residue obtained with gasolinewhen only benzine and lamp oil have been distilled off, to cool and thento centrifuge. Although in this case the material does not suffer somuch as from cracking, temperatures are used that cause decompositioMethods that involve dilution? by gasoline naphtha),ha\fe thedisadvantage that they require large quantities of gasoline `and twodistillations; benzine and kerosene being first distilled off from thecrude-oil and then about the same quantity of gasoline being added todilute thev residue. Consequently, large 'distilling plants and largequantities of fuel are required.

The usual methods for refining the paraiin are also objectionable. It isgenerally believed that thegparaflin is contained in the .paraiiindecreases as its melting point is lowered, a loss to crude oil mainly inamorphous form, and therefore distillation is used to convert theamorphous paraflin to crystallized paraiiin,

which can then be freed from the oil 1in several A' ways. 4The ldrawbackof this method is that the paraiiin, which exists ir the residue in ahighly viscous solution, must be exposed to an intentionally destructivedistillation, in order to obtain it in the form of suilicently largecrystals for the subsequent refining process. This procedure producesparaflin of relatively low melting point and oil of relatively low`viscosity. Inasmuch as the market price of the manufacturer is involved.v p y The present invention comprises a method of manufacture by which amaterial free from or poor in paraffin is obtainable for the manufactureof lubricating oils, and by which a material rich in paraliin, and witha low viscosity, may be obtained for the manufacture of paraiiin, andwherein the double dis-I tillation above mentioned is avoided; Wherebythe viscosity of the oil, as well as the structure of the paraincontained in the crude oil,

can be completely preserved.

These advantages are obtained by separating the paraffin directly out ofthe crude oil. When the latter has been relieved of water and solidimpurities-by centrifugation or by some other means-it is Cooled so that'the paraliin contained in it is precipitated in a solid state and canbe separated by centrifuges. If the process is applied to crude oilsthat contain relatively small quantities of light components, a dilutingagent, for linstance gasoline, may be vrequired to make the oilsuiiiciently free flowing to allow .centrifugation. c

The invention-does not exclude the primary treatment of the crude oil,with chemicals or in some other way, in order-,for example, to vfree itfrom any asphalts contained therein, or from ingredients or unsaturatedhydrocarbons similar to asphalt'.

s If the crudeoil itself contains crystalline paraffin, it is possibleto let the same crystallize by slowly cooling it while preventingdisturbing effects as far as possible, and in this case a fractionalseparation of the paraiiin can be effected by two centrifugations. Forthis purpose so much material per unit of time is passed through theseparator in the first centrifugation that mainly the paralfln crystalsalready formed and harder parailins are thrown against the bowlwall,`while oil from or poor in paraiiin is discharged from pointedout-retains all the characteristics of the crude oil except the paraffinconstituents, can then-be treated, in order to obtain oil productsinclusive of lubricating oils, in' accordance with any known treatmentof anatural paraiiin-free crude oil. The'output of paraffin-free crudeoil obtained in this Way, i. e; without any dilution with gasoline, or,at least, with relatively smallquantities of a dilution'liquid, is about8O to 90%, according to the content of paraiiin in the original crudeoil.

The mass which, in the centrifugal operation, is thrown on the'bowl wallcontains a; considerable proportion 'of highly viscous `oi1.

A further step in the process involves a substantial reduction in theproportion of thisV viscous oil inorder to render the paraiin moresuitable for subsequent refining. To this end, the centrifugallyseparated paraiiin mass is diluted with any material (for instance,gasoline) that will dissolve the oil. and the'mixture of parailin andsolution of viscous oil4 and gasoline is centrifuged. As i the paraiinmass obtained in the first centrifugal operation is already well cooled,it

vis advisable to cool the dissolving or diluting liquid separately, andto add it in a cooled condition. For ,certain kinds of crude oil,however, itvmay be of advantage to dissolve theparaliinmass in gasolineat a higher temperature, and to precipitate the paraiiin by anothercooling process.

If the quantity of viscous oil in the paraiiin mass obtained in thelast"described centrifugation is still too high, the mass may be dilutedand centrifuged once more. The

procedure is repeated until a product usable l for the subsequentrefining process is obtained. As' the parailin-free liquid obtained byrepeated centrifugations naturally becomes more and more pure, -i. e.contains after each. centrifugation, a smaller proportion of'heavyhydrocarbons than is contained in the product of the precedingcentrifugation, it is advisable to use, for instance, theparaliin-free'liquid from the third centrifugal operation (the secondcentrifugation of the diluted paraiiin mass)V as a diluent for thesecond centrifugal operation (the first centrifugation of the dilutedparaflin mass) in order to economize with the diluting liquid `anddistillation. v

The following is a specific example of a process conducted in accordancewith the general -description hereinbefore given:

It may be assumed that we start with crude oil capable of being treatedwithout dilution. Any traces of parafiin that may be contained in theparaffin-free liquid obtained by centrifugatlon are ignored. It may belfurther assumed that, in the operation of centrifuging the crude o il,theparafiin mass obtained contains fof paraffin, although, in practice,this percentage will Evary. Two examples of treating the paraffin massthus obtained in the centrifugationofcrude oil may be given:

(l) Dilute once and centrifuge.' This treatment involves two centrifugaloperations in the entire process.

(2) Duur@ and centrifuge twice. This'` treatment involves threecentrifugation operations in the entire process.

In the second example, the first dilution is effected with paraiin-freeliquid taken from the third centrifugation: In order to render theresults obtained in the two instances comparable, such predeterminedquantities of diluting liquid are added that in -both cases the samequantities of material will be centrifuged.

Starting with crude oil of the following composition A Per cent Benzine14 Paraffin Other hydrocarbons 83 The compositions of the separatedconstituents after the first centrifugation are as follows:

(a) Paratlin- (b) Paraln free liquid mass Kg, Ka. Benzine `13. 35 .14. 40. 65 8. 7 Paran 3. 40. 0 Other hydrocarbons 79. l5 85 6 3. 85 51. 3

E :comple of single centrifugation ofparaf- )in masa-The parailin mass'(b) is diluted with 45 kilograms of benzine, the whole being thensubjected to centrifugation. Constituents of the followingcompositionsare obtained:

(c) Pqrain- (d) Pai-annu treelxqmd mass A Kg. '7 K Benzine 41.50 924.015 yaa Parain 3.a) 40.0 Other hydrocarbons .3.50 7.8 0.35 4.7

Eample of multiple cenz'fugatzon onf pa'rayfn masa-The paraffin mass (b)obtained in the first centrifugation is diluted with .18.75 kilograms ofthe. paraffin-free liquid obtained by the thirdcentrifugation mentionedbelow. This liquid contains 18.05 kilograms of benzine and 0.7 0kilograms of lother hydrocarbons. The thus diluted parafiin massmentioned has the following com The paraain mass (f) is duur-.ed with18.75

kilograms of benzine` and centrifugated, this being the thirdcentrifugation.

The separated 'constituents have the following compositions: i

(a) Paranf (h) Paran free liquid mass Kg. 7 Kg. '7 Benzine 18. o5 96.0254. 33 si. Parafn 3. 00 40. Other hydrocarbons 0. 70 3. 75 0. 17 2 .Ifthe benzine is distilled off from the paraffin masses (d) and (It)Vparaffin masses -of -the following compositlons respectively v areobtained First example `Second example K u. 7 Ku. 7 Panam. am 85.5 3.0031a O ther hydrocarbons 0. 35 10. 5 0. 17 5. 4

Ifthe c rude' oil contains too small a proporvtion of lightcomponents-to be directly centrifugated, it is advisable touse aparafiinfree iquid obtained in a' subsequent-operation as a dilutingagent, gasoline being saved 1n this way and, consequently, thedistilling costs reduced.

rl `he invention is not limited in its application to crude oils, butcanalso be used advantageously forv treating paraflin-containing tars,mineral coals and lignites, shales and other bituminous materials.

The applicability of the method is not dependent on the use of coolersand centrifugal s ssa separators of special construction, the methodbeing workable with coolers and centri.-

` fuges that have been heretofore used in the uidsrunning from theseparator may be used' to pre-cool the-base material lor thedilutinmeans.

owls with disks and bowls without disks may be used for thecentrifugation, the first mentioned bowls being preferred o n account oftheir higher eliciency. It is of 'course advantageous to use centrifugesfrom which the paraiin mass as well as the'vparaiiin-free li uids maybe; discharged continuously; but 1t is also practicable to usecentrifuges wherein the paraliin'mass accumulates on the wall of thebowl, whence it is discharged-.periodically, if necessary after stoppingthe bowl.

On account of the consistency of the parain mass, its continuousdischarge from the bowl does not generally offer any diliiculties. -Insome cases 1t may be advantageous, however, when working continuously,to have recourse to special means in order to facilitate the dischargevof the paratiin mass. For in-l stance, mechanical auxiliarvmeans may'be used in order to scrape off the mass from the bowl wall and to bringit toward the center,

. is being continuously dischar whence itmay be led away withoutdifficulty. -It is alsopossible, however, to'tloat o ut the massor towash it out. In the floating operation, a liquid, cooled down to asuitable temperature, is introduced at the outer wall of the bowl. Theliquid must have a higher specific gravity than the paraiin mass.

A traveling cushion is then formed on which the mass floats and togetherwith which it is discharged. This procedure, however, has the drawbackthat it may be dilicult attimes to separate the paraiiin mass from thecushioning liquid without impairing the quality of the former.

This inconvenience can vbe avoided if the paratnmass is sludged out byutilizin the paraiiin mass already obtained by centri ugation as asludgin'g liquid. It will be understood that it is desirable, where theparan wed, to so constrict the outlet for the paratflin relative to theoutlet for the lighter oil, that the paraffin mass will be as rich inparalin as possible. In such case, the quantity of the parain mass maybe so small and, consequently, the velocity thereof so low, that largeparaffin crystals, if there are any present, may stick to the vouterwall of the bowl and accumulate thereon. If, however, the velocity offlow is then increased by t-he addition of .a large quantity of theparaffin mass that has been already centrifugated, any paralin crystalsadhering to the bowl wall will be torn off or they will 'ing liquid, maybe reduced.

the paraffin mass,'wholly or whose constituents are to be centrifugallyAseparated. In bowls with disks, it is there- -foreadvantageous tointroduce th'e ysludging l'iquidbetween the outer bowl wall and thedisks. If this 'space'adjacent the bowl wall be divided into a number ofaxial channels, the transverse section'of the'partition walls and,consequently, thev quantity of the sludg- VThe discharge of theparafinma'ss can also befLacilitated by reducingthe viscosity of the'mass This may be obtained by the arrangement of a heatingsurfaceelectve to melt partly. This method can also be used inconJunction with a sludging liquid, which in this case could beintroduced at a'. somewhat higher temperature than that of the separatedparatlin mass. It i s,vhowever, always necessary to regulate theapplication of heat in such a way that the annular wall of paraflinimmediately adjacent the inner' or centralzone of oil will not be soraised irl-temperature as to go into solution with the oil with which itcontacts. For

example, the temperature ofthe Asludging liquid may be just sufficientlyhigh to melt layer of parailin adjacent to the'oil.

The bringing of the sepa-rated parallin mass to and out the center ofthebowl is facilitated if the same be required to "flow through a number ofradially or conically arranged vantage when the above-mentioned space isnot divided into axial channels. Suchdevices to increase the velocityofthe paraiiin mass olfer advantages in cases where no sludging liquid isused. i Treatment of amorphous paraji'm, materials,

ott-containing waxes, amt otherv materials the layer of paraliinadjacent to the sludging liquid but not high enough to melt the channelsat a comparatively high velocity.

The said channels may also be used to ad containing paran, to producerened sweating of the masses diiiicult, this distillationmust take placeat a high temperature, wlth a partial destruction of the highly viS-cous oil, which causes the paraiins to be partly destroyed and theirmelting points to vbe lowered.

In the process involving our 'invention the highly viscous oil is washedout of the paraffin i' ing a reduction of the viscosity of such oilmasses, permitting subsequent and very careful distillation of themasses, thereby avoidform.

In accordancewith our process, the paraffin masses are first freedfrom'water and solid impurities,` by centrifugation, 'or' in some otherway. *d

The paraiiin masses are then diluted with a light hydrocarbon liquidcapable" of dissolving the liquid hydrocarbons in-the paraiiin mass, forinstance, with1 gasoline (naphtha) whereupon the masses are cooled. Theparaffin is thus/precipitated in a solid state, and is removed.. fromthe liquid mirri` In certain cases it may be useful to separately cooithe ture by means of centrifuges.

paraliin 'mass and-the diluent liquid and to mix them in a cooledcondition.

If the mass contains crystallized as well as amorphous paraiiin, it maybe preferableto use fractional centrifugation. For this purpose thediluted paraiiin mass is first moderately cooled and centrifugated, inwhich operation substantially all the ,crystallized paraffin isseparated. Then the material from which the crystalline mass has beenseparated is cooled to a lower temperature and the remaining parafhn isseparated by centrifugation. In "the first operation the centrifuge isrun at a relatively high capac-A ity, and the second operation at arelatively low capacity.

It is obvious that of the added diluent hydrocarbon, the greater thereduction in the content of highly viscous oil, and as the Iparaiiinmass centrifugated out` at' the/bowl wall contains an oil of' the samecomposition as does the dilutedy mass before centrifugation, the contentof highly viscous oil in the separated paraffin mass will becorrespondingly reduced.

If necessary, the crystalline mass obtained afterv the firstcentrifugation, is again diluted, cooled an'l centrifugated. The secondycentrifugation (of the; remaining paraffin) may lfalso be fractional.In each case the centrifugation may bel repeated until the paraffin massis sufficiently freed from highly viscous oil to allow offurtherrefining.

The amorphous paraffin is then distilled in order to convert it tocrystals: In order to facilitate thisdistillation and to better protectthe paraffin against splitting (which it. vis desired to avoid), an oilof a viscosity and 4 of a boilingpoint lower than those of the sparaffin may be added to thaparaiiin mass before'distillation. The addedoil then dissolves the parailin, and the solutionrdistils.J

that ati which at a lower temperaturethan the paraffin alone willdistil.

the greater the amount The paraiiin mass obtained in the distillationprocess may be freed from the oil either by filtering or sweating (whichhitherto has been the usual procedure) or preferably, by theabove-described` treatment comprising dilution, cooling, andcentrifugation, which may be repeated until a' salable product isobtained. As of coursefthe paraffin-free liquid' obtained by repeatedcentrifugations becomes more and more pure, i. e. contains after eachcentrifugation, a smaller proportion of heavy hydrocarbons than afterthe preceding centrifugation, it is preferable to use the ods used inthe refining of crude oil, and such .refining treatment may either takeplace be- `fore the first centrifugation, or at some other stage in thecomplete process above-described, according to the natureof the paraffinmass to be treated. Y

Treatment*- of amorphous paran masses, oz'Z- eorztaz'm'ng wares andother materials een taining para'n, to produce refined amorphous paraynwith a'hzgh melting point It is believedl that no method exists which iseconomically workable on a commercial scale for producing, from naturalor artificial amorphous paraffin masses, refined `amor-- phousparafiinwith a h'igh melting point. Therefore, such paraiiin. masses areat present mainly used as insulating masses, and for similar purposes,whereas natural oil-free amorphousparaiiin has a high value on accountof its high melting point, and in a refined condition it is much highervalued than paraffin. i

Inv order to producev refined amorphous paraffin of high melting point,the process involving our invention is so applied that the amorphousparaffin in the oil-containing' 'masses is freed from oil withoutaltering the structure of the'L paraffin. The invention is alsoapplicable to such paraffin masses that contain, inaddition to amorphousparaliin, parain in crystals or in some other form.

The paraffin mass is first freed 'from water after -which it is cooled.The parain is thus recipitated in a` solid condition and may be removedfrom the diluted massby centrifugation. In certain cases'it is advisableto cool the paraiiin mass and the diluent liquid separately and to mixthem together in cooled condition.

If the parailin mass contains crystallized lparaffin, or amorphousparaflins of different ardness, it may be of advantage to use fractionalcentrifugation.' For this purpose the diluted mass is' first moderatelycooled and centrifugated, in which operation the harder paraflins willbe separated.' /Then the material from which the paraiiins have beensep-1. arated is further cooled and the remaining paratlin is separatedby a second centrifugation. y If the parafn mass separated out in thefirst 1centrifugation. is not of the `required quality, it is diluted,'cooled 'and again centrifugated. A similar fractional centrifugaltreatment m'ay be applied to the softer amorphous parahn separated outin the second centrifugation. In each case the operation is re ateduntil, after themixture entrained has een ejected, a marketable product'is obtained. As of course the paraiin-free liquid obtained by repeatedcentrifugations becomes more and more pure, i. e. contains, after eachcentrifugation, a smaller proportion of `heavy hydrocarbons than afterthe preceding cen-. trifu ation, it is preferable to use the paraflin-`ree liquid obtained in'a subsequent centrifiigation as a diluent for apreceding centrifugation. In this way'economy is attained iny theuse ofdiluting agents and also with. respect to the distillation and the fuelcon. sumption.

. With paraffin masses,A containing -large quantities of asphalt, itmaybe useful to divide the chemical refining into two or more .yoperations. The workvmay, for instance, be

'performed in the following way.

vThe paraiinmass to be treated, after water and solid impurities haverst been removed, is dil/uted, cooled and centrifugated, in order toremove afportionlof the highly viscous oil Vcontained in the mass, andthus facilitate the action of the reagents used. The parailin massobtained from the centrifuge is then .f subjected to chemical refining,whereby the mainportion vof the asphalt is removed, thus i facilitatingseparation'of the paraiin'in the subsequent centrifugation process. Ifthe mass has not been diluted in connection with the refining operation,it ,is diluted, and

cooled and again centrifugated. According to the properties ofthe massand the result aimed at, the mass obtained in this operation is eithercentrifugated again, or else subjectv ed, at this stage, to strongerchemical refing.

ing, whereupon'theprocedure comprising di'- lutlon and centrifugation iscontinued until amarketable product is obtained.-

Treatment of dz'stz'llates or resz'duum (containing parayin) from crudeoil o'r tar, to

produce high grade pamW of uniform composition lVhen using the methodshitherto employed for obtainin paraffin out of s ome `crude material, amixture of the different parafiins contained in such material isobtained. As

these paraliins have melting points varying-- Within wide limits, amixture is obtained having a melting point near that of the paraiiin-Which melts at the lowest temperature, which of course means a loss tothe manufacturer, in that the market prices of paraiiins increase withtheir melting points.

By proceeding in accordance with the present invention, we secure, bymeans of fractional cooling and centrifugation, isolation of practicallyuniform paraffin out of distllates, as Well as residues, from crude oil'or tar.

W'e proceed by taking the material from ing it to a temperature at whichonly paraiiins of the highest melting points are precipitated in thesolid state. After these have been separated by means of centrifugation,the liquid, freed from solid.. ingredients, 'is cooled :tage to splitthe paraffin, first into one or a.

few fractions, in the way described, from the Startingmaterial, and thento separate the rough fractions obtained by the following,

treatment; The paraffin masses obtainedv are diluted with-a suitableliquid, such as gasolin/e, 'which dissolves liquid hydrocarbons, andthen are fractionally cooled and cent-rifugated. Itisthereby possible toseparate the parailins, with regard to the melting points,

which the paraliin is to 'be isolated and coolto the degree desired; theadvantage of the `procedure being that thehigh7 viscous oils Y arewashed oi, allowing refining of the paraiiin to be readily effected inaccordance with known methods. 1 s

The method described above has, especially in the treatment ofdistillation' residuums of high viscosity, the advantage over ordinarymthods that part ofthe paraffin is removed at higher temperatures, andwhen loW--' er temperatures are made use of, only a relathe liquid fromwhich the paraffin has been largely separated, and consequently thematively small proportion 'of parailin remains in teri al remaining tobe centrifugally treated is maintained in a relatively fluid conditionand therefore requires little or no dilution. Otherwise, thedistillation of large quantities of diluting liquid AWould becomparatively' costly. l

In order to diagrammatically show two Vcomplete Iprocesses comprisingdifferent alternative embodiments of our invention, containing essentialas Well as non-essential but preferential features, a.di'awin isattached hereto which, in connection' wit the foregoing description,`requires no special description.

What we-claim as newand desire to secure by Letters Patent is 1. The-process of separating paraffin from hydrocarbon material containingparaffin and' other hydrocarbons, which comprises diluting thevmaterialwith' a liquid hydrocarbon,

cooling the diluted material to a temperature adapted to precipitate apart of the paraffin, centrifugally separating the parain ina-sscontaining said precipitated paraffin from a lighter specific gravityconstituent contain ing the remaining paraffiny and the bulk of theother hydrocarbons, cooli-ng such remaining material to precipitateadditional paraffin, centrifugally separating from suchgremainingmaterial the paraflinmasscontaining the paraffin precipitated by thesecond'cooling from a lighter specific gravity constituent comprising asubstantially paraffin-free liquid, adding a diluent to the secondparaffin mass and centrifugally separating paraffin from a lighter-specific gravity constituent comprising a substantially paraffin-freeliquid, and in the course of the foregoing operation utilizing thelighter specific gravity constituent separated out in a latercentrifugation as al diluent preparatory to an earlier centrifugation,and utilizing the paraffin 'mass 'separated out in a latercentrifugation to facilitate, in an earlier centrifugation, the removalofthe centrifugally separated paraffin mass /t'rom the locus ofcentrifugation; distilling one of said paraffin masses containingamorphous paraffin at the temperature required to convert amorphousparaffin to crystalline paraffin, diluting the'crystalline parafiin massand cooling to precipitate-'the crystallineparaffin, andcentrifuging toseparate f the crystalline paraiiin;

material containing such paraffin in both amorphous and crystalline ormand other hydrocarbons, which comprises diluting the material with aliquid hydrocarbon, cooling the diluted material to a temperatureadaptedl to precipitate crystallized paraffin, centrif` ugallyseparating such crystallized parafn, cooling the remaining material to alower temperature to precipitate the remaining paraffin, andccntrifugally separating the paraffin precipitated in the secondcooling.

4. The process of separating paraffin from material containing paraffinand viscous hydrocarbons, which comprises cooling said materia-l toprecipitate paraffin, centrifugally sepa ating a paraffin mass,comprising precipit ted paraffin and some of said viscous hydrocarbons,from the bulk of said viscous hydrocarbons. adding a diluent capableofdissolving hydrocarbons to the centrifugally lseparated paraffin massto reduce itsl proportional content ofsaid viscous hydrocarbons, andcentrifugally separating, from the diluted paraffin mass, paraffincontaining a relatively smally proportion of said viscou hydrocarbons.

5. The process of separating paraffin from materia-l containing parafnand otherhydrocarbons, which comprises adding a diluent and cooling toprecipitate parain, centrif- `ugally separating from the dilutedmaterial the paraffin mass containing precipitated paraffin and some ofsaid other hydrocarbons, adding a diluent capable of dissolving hydro'carbons to the centrifugally separated parafin mass to'reduce theproportional content 'of said other hydrocarbons in the resultantmixture, and centrifugally separatingl from the dilut-ed paraffin massparaffin containing a relatively small proportion of said otherhydrocarbons; the material from which the paraffin is separated in thelast mentioned centrifugation boing used asa diluent for the materialwhich is subjected to the first men.

tioned centrifugation.

6. The process of separating paraffin fromr material containing paraffinand ther hydrocarbons, lWhich lcomprises cooling the -material to atemperature adapted to precipitate( ,pal'affin, centrifugally separatingthe paraffin mass, comprising precipitated )araffin and some of/s'aidother hydrocarbons, from the bulk of saidother hydrocarbons, adding adilu'ent capable of dissolving hydrocarbons to the centrifugallyseparated paraffin mass to reduce the proportional content of said otherhydrocarbons in the resultant mixture, centrifugally Iseparating fromthe diluted paraffin vmass paran containing a smaller proportion of saidother hydrocarbons than was contained in the first paraffin mass,add-img a similar diluent tothe paraffin mass sep-Vv arated out by fthesecond centrifugation. and

centrifugally separatin g from the last named diluted paraffin massparaffin containing a' still smaller proportion of said otherhydrocarbons'. i.

7. The process of separating paraiin from material containing paraffinand othenhydrocarbons, which comprises cooling the material to atemperature adapted to precipitate paraiiin, centrifugally separatingthe paraiin mass, comprising precipitated paraflin and some of saidother hydrocarbons, from the 1 bulk of said other hydrocarbons, adding adiluent capable of dissolving hydrocarbons to the centrifugallyseparatedparaffin mass to reduce the proportional content of said otherhydrocarbons in the resultant mixture, centrifugally separating fromthediluted paraffin mass paraifin containinoP a smaller proportionv ofsaid other hydrocaiibons than was contained in the first centrifugallyseparated parailin mass, adding a diluent capable of disfsolvinghydrocarbons to the paraiiin mass separated out by the secondcentrifugation to still further reduce the proportional content ,of saidother hydrocarbons, and centrifugally separating'from the .last nameddiluted parailin mass paraffin containin a still smaller proportion ofsaid other hy rocarbon's; thek material from which theV paraffin isseparated in the last mentioned centrifugation being used as thespecitied diluent for the material 3 which is subjected to theimmediately preceding centrifugation.

8. The process of separating paraffin from material containing paraiiinand other h drocarbons, which comprises adding to sai material a diluentcapable of dissolving hydro.-

carbons and cooling to precipitate paraiiin containing a reducedproportion of said other hydrocarbons, centrifugally separating the'paraffin mass, comprising a diluent and some 40N of saidotherlhydrocarbons, from the bulk of Y said/hydrocarbons, adding "adiluent capable of dissolving hydrocarbons to the centrifugallyseparated paraflin mass to further re- .duce the proportional content ofsaid other hydrocarbons in the resultant mixture,centrifugallyseparating from the diluted parafv infmass paraffincontaining a ,smaller proportion of said other hydrocarbons than Was--contained in the first centrifugally separated paratn mass, adding'. adiluent capable of dissolving hydrocarbons to the'paraflin massseparated by the second centrifugation to still further vreduce theproportional content of i said other hydrocarbons, and centrifugally 5separating from the last named diluted parain mass paraiin containingastill smaller proportion of saidother hydrocarbons; the materialfromrwhich theiparalin is separated in one ofthe later specifiedcentrifugations being used 'as the diluent for the material which issubjected totali earliei` centrifugation.

9. y`The process-of separating paraffin from,

material containing .paraiin in both amor- 65. phou'sand Icrystallineformand other hydrosaid precipitated paratlin from the remaining vmaterial, cooling the remaining material to precipitate amorphousparaffin', centrifugally separating the mass comprising the parailnprecipitated in the second cooling from the remainlng material, anddiluting one of said paralin masses with a liquid hydrocarbon andcentrifuging to recover the paraiin more nearly free of said otherhydrocarbons.

10. The process of separating paraiiin from material containing paralinand other hydrocarbons which comprises diluting the mates rial With aliquid hydrocarbon, cooling the material to precipitate crystallizedparaffin, centrifugally separating the mass comprising saidprecipitatedparain from the remaining material, cooling the remaining material toprecipitate amorphous paraiiin, centrifugally separating the masscomprising the paraiiin precipitated in the second cooling from theremaining material, diluting one of said parailin masses with a liquidhydrocarbon and centrifuging; and utilizing the constituent of lighterspecific gravity separated in a later centrifugation as a diluentpreparatory to an earlier centrifugation.

il. The process of separating paraiiin from material containing paraiiinand other hydrocarbons, which comprises adding a diluent capable ofdissolving hydrocarbons and cooling to precipitate paraffin,centrifugally separating the paraffinmass, comprising parain and some ofsaid other hydrocarbons, from the bulk of said other hydrocarbons,thereby reducing the proportional content of said other hydrocarbons inthe\paraiin mass, re-

peating the, diluting and separating operation on the separated paraiiinmass, and utilizing a paraffin mass that has been 'so separated out inone operation tofacilitate the removal in anotheroperation of thecentrifugally sep-` arated parain mass from the centrifuge.

12. The process of separating paraffin from material containing paraffinand other h vdrocarbons, which comprises adding a diluent capable ofdissolving hydrocarbons and cool-- ing to precipitate paraffin,centrifugally separating the parain mass, comprising paraiiin and someof sai-d other hydrocarbons, from ythe bulk of said other hydrocarbons,thereby reducing the proportional content of said other hydrocarbons inthe paraflin mass, repeating the diluting and separating operation onthe separated parai mass, utilizing a paraffin mass that has been soseparated out in; one operation to facilitate the removal in Ianotherseparation of the centrifugally separated paraitin Imass from thecentrifuge, and utilizing the lighter specific gravity constituentseparated in a 'later centrifugation as a itY ' distilling diluentpreparatory to an earlier centrifugation.

13. The process of separating paraffin from material containing paraiinin both amorphous and crystalline form and other hydrocarbons, whichcomprises diluting the material with a liquid hydrocarbon adapted todissolve said other hydrocarbons, cooling the material to precipitatecrystallized paratin, centrifugally separating the precipitated paraflinfrom the remaining material containing the remaining paraffin, coolingthe remaining material to precipitate amorphous paraffin, centrifugallyseparating paraliin precipitated in the second cooling lfrom theremaining material, diluting the parailin that has been centrifugallyseparated at the lower temperature with an -oil of aiiv'isc'osityandboiling point below that of the paraffin, distilling the solutionthus formed at the temperature required to convert the paraffin to acrystalline state, and separating the last Amentioned crystalline parahnfrom the major part of any other hydrocarbons with which it isassociated vafter the distillation.

14, The process of securing crystalline paraliin from materialcontaining amorphous and crystalline paraflin and other hydrocarbons,which comprises adding a diluent capable of dissolving hydrocarbons,subjecting the diluted material to centrifugal treatment and chillingrequired to separate a paraifinmass of which the paraflin is mainlyamorphous,

the paraiiin mass at the temperature required to convert amorphousparaiin to crystalline paraiiin, and separating the crystalline paraiiinother hydrocarbons with which it is associated after the distillation. i.l

15. The process of securing crystalline paraiiin from materialcontaining amorphous and crystalline parailin and other` hydrocarbons,whichcomprises adding a diluent capable of dissolving hydrocarbons,subjecting the diluted material to centrifugal treatment and chillingrequired to separate a paraiin mass of which the paran is nainlyamorphous, distilling the paraiiin mass at the temper'- ature requiredto convert the amorphous parain of the mass to crystalline paraffin,diluting the' parailin mass with a solvent liquid having a viscositybelow that 'of the paraffin, cooling to'precipitate the crystallineparaffin, and centrifuging to separate the crystalline paraffin from thediluting agent and`other hydrocarbons with which it is associated afterthe distillation.

16. The processof producing crystalline paraliin from hydrocarbonmaterial containing amorphous and crystalline paraiiin and otherhydrocarbons which comprises diluting the material with a solvent liquidhaving a viscosity below that of4 paraiiin, cooling the dilutedmaterial, centrifugally .separating u from said material a paraiiin massconstituent from the major part of containing some of the parain and alighter specific gravity constituent containing the remainder of theparaiiin, taking the lighter of said constituents and repeating theoperation applied t'o the original material until there is separated amass containing parain which is mainly amorphous, distilling said massat lthe temperature required to conving amorphous and crystallineparailin and other hydrocarbons, which comprises diluting the materialwith a solvent liquid having a viscosity below that of the parain,cooling the diluted material to a temperature adapted to precipitateparalin, centrifugally' separating-a constituent containing saidprecipitated paraffin from a lighter specific gravity constituent,centrifuging one of said-separated constituents and thereby separating aconstituent containin amorphousparain from a dierent speci c gravityconstituent, centrifuging thelast named constituent and therebseparating an amorphous parain mass rom a relativelynparan free liquid,utilizing the lighter specific gravity liquid constituent separated outin a later centrifugation as a diluent preparatory to an earliercentrifugation, and distilling the amorphous paraffin mass at thetemperature required to convert amorphous paraln to crystallineparailin. l s A 18. The method of separating parains from liquidhydrocarbonswhich comprises so subjecting oil lto distillation andchilling as to produce liquid h drocarbon fractions containingprecipitate parailins that to a substantial extent are in crystallinecondition, subjecting the chilled crystalline paraffin-containing liquidhydrocarbons to centrifugal force to eiect a separation of the bulk ofthe parailin from the bulk of the liquid hydrocarbons and, while thecentrifugal force is operative, subjecting the separated parafn to amechanical action adapted to' facilitate its expulsion from the lo'cusof centrifugal separation. v

19. The method of separating parains romfliquid hydrocarbons whichcomprises subjecting oilto fractional distillation and thereby producingliquid hydrocarbon fractions containing readily lterable parain andother liquid hydrocarbon fractions that contain paran not readilyvilterable, chilling the latter to precipitate the paraiiin andsubjecting the chilled parain-containino' liquid hydrocarbon fractionsto centriiugal force to eiect a separation of the bulk of the paraiinfrom the bulk of the liquid hydrocarv bons, and, while the centrifugalforce is operative, subjecting the separated parain to a mechanicalaction adapted to facilitate .its expulsion from the locus ofcentrifugal sep(- aration. A

' 20. The improvement in the treatment of 5 petroleum oils for theremoval of paraffin wax contained therein, comprising ubjecting the oilto a crackin treatment' toconvert at least a portion o the Wax containedtherein to a crystalline formsubsequentll lo chilling thel oil and.subjecting the cold oil to centrifugal force whereby the wax and waxfree oil are separated into layers, me-

- chanically discharging the wax in substantially sol1d form from thezone in whichit is f subjected to centrifugal force in a continuous jmanner at one point with movement toward the axis of rotation,' andcontinuously dis# ycharging the wax free oil. from said zonewithmovement toward the axis of rotation at an- '2b other point.

21. The improvement in the treatment of petroleum oils for the removalof parain wax contained therein, comprising subjecting the oil to acracking treatment to convert atV least a portion ofthe wax to acrystalline form, subsequently chillin the, oil in the vpresence of adiluent an subjecting the chilled mixture to centrifugal force wherebythe wax and wax free oil ancldiluent are sep-'- arated into layers,mechanicall discharging A the wax in substantially solid orm from thezone in which it is subjected to. centrifugal force at one point in acontinuous manner with movement toward the aids of rotation andcontinuously discharging the wax free oil anddiluent from said zone withmovement toward the axis of rotation at anotherpoint.

22. The improvement in the treatment vof petroleum oils for the` removalof parain vwax contained therein, comprising subjecting the oil to acracking treatment to convert at least a portion of the wax to acrystalline form, subsequently chilling the oil 1n the presence of a lowboiling naphtha and subjecting the chilled mixture to centrifugal forcewhereby the wax and wax free naphv tha-oil solution are separated intolayers, mechanically discharging the`wax in`substantially solidform fromthe zone in which itis subjected to centrifugal force at one point in acontinuous manner with movement toward theaxis of rotation andcontinuously dischargin the wax free naphtha-oil solution from said zonewith movement toward the axis of rotation at another point.

In testimonyl whereof we ax oursigna tures at Stockholm, Sweden, this25th day of Apri1,1924. A

HANS OLOF LINDGREN. vKNUT GUSTAF MALM.

